Excavator



Dec. 26, 1950 T. c. MULLINS ET AL EXCAVATOR 2 Sheets-Sheet 1 Filed Feb. 25,. 1946 Dec. 26, 1950 T. MULLINS ET AL 2,535,750

EXCAVATOR Filed Feb. 25, 1946 '2 Sheets-Sheet 2 fade/21%: 12m 6'. W

Patented Dec. 26, 1950 UNITED PATENT 0E F ICEv 2,535,759 EX A TQR.

Thomas G. Mullins, Chicago, and; William E. Masha J Chester,

Application February 25, 19.46, ScrialNo 649,813 S Ql aim s. (01. 212-66) This inventionrelates to. improvements in ex, cavating machines.

In excavating machines. of the drag lineor. shovel type. provided with a supperstructure. that swings about a vertical axis in depositing successive loads, a stationarycircularrack or. ring gear generally is provided in the lower declsor carriage substructure, of, the. machine which, in. cooperation with a number of. motor. driven pinions in theupper deck. or superstructure, produces. the. swinging movement in thedirection. desired; The motors that drive. the pinions that mesh with. the. circular rack generally are. orthe reversible type under control of. theopera:v tor. of themachine.

In large excavating machines of. the type mentioned, such as are employed for example. in strip mining and having booms from 100 to185ieet in length that support buckets orclippers. upto.

39 or more cubic yards capacity, the stresses imposed on the pinions and racks. aretremendous. In a single such machine. used in strip mining the cost of repairs and replacementsof pinions andracks has exceeded $10,000.00. in a.

single year.

The rate of loading aushovel or dipper, by an. operator, and the time required for-discharge by. gravity of, the loads. are substantially-fixed; and hence, attempts to. increase the. worhdone by. a. given machine. generally have consisted in ace. celerating the. .rate. of. swingof the. superstructnrcbeilween successive loads. However, by ac, celerating. the rate .of swinging movement to and. from load discharging positions, proportionally. greater forces are. imposed on the rackand gears, and. hence the durability .of the latterare alimiting factor in theearth moving capacity. of the machine.

Itis an object of the present invention taprovidemeanswhereby the swinging movements of such excavating apparatus can. be accelerated and decelerated above thepresent safeornor mal rate not only without imposing additional stresses upon the racks and-pinions, but whereby such stresses may actually be reduced, and thereby not only. directly increase the working capacity of the machine, but-increase the capacity indirectly also by reducing the time lost by shutdowns for. repairs. referred .to above.

In utilizing the improvements there is provided one-.orcmorecontrollable power units that'opcrate propellers or air screws mounted-on'the machine for producing swinging efforts or forces that are additive to the forces-delivered -by the usual pinions-that'normally produce the swing- 2. ing movements or the superstructure which carries the bucket or dipper.

the improvements.

Figure 1 isa side elevation of a drag line ex cavator provided with three power operated-1 air. screws orpropellers which are so positioned and operable as to cooperate each with the other and with the conventional gearand-pinion mecha.-. nism. in. swinging the superstructure about its:

vertical axis.

Fig. 2-.is a broken top .plan view. of the power unit and'propeller that are mountedlon the outer end of the boom in Fig. 1, asviewed along line. 2-2 of Fig. 1, such unit being similar to the.

other two units shown. in Fig. 1, one. near the rear end of the boom and the other at the rear.

end of the superstructure.

Fig. 3 is an enlarged broken top plan view of;

any one. ofthe threepropellers shown in Fig. 1;

exert aswinging effort in a selected direction;

Fig. 4 is a. side elevation .ofanexcavator, of. the shovel type. showing propellers arrangedxin, opposed pairsior exertingswinging forcesin.

either direction by the selected operation of co= operating propellers.

Fig. .5 .is a brolren top plan view. of .a pair of propellers and operating power-units=therefor shown at the outer end of the boom in Fig.- 4..

Fig. 6 isatop plan view of 'thetpower units shown atthe rear of the superstructure. in-Fig. 4.

Fig. 7 is a. detachedview of=a propellerand driving. unit therefor, comprising a. reversible; electric motor that maybe employed in lieu of any of the other. propeller units illustrated inthe foregoing figures.

Fig. 8 is a diagrammatical view of another pro peller driving unit.

In Fig. lor the drawing, l0 indicates generally an excavatingmachine of the drag line type comprising a swingable superstructm'e H and a substructure or carriage 12, which constitutes The,

the mobile -mechanism of the excavator. superstructure II is supportedon the carriage I2 ior movement abouta vertical axis indicated riage land atplurality of pinions carriedby;

the superstructure H. Such structureWis-con In the accompanying drawings thestructures shownare illustrative ci ventional and in Fig. 1 two pinions only are shown, although in some machines a greater number is employed. In Fig. 1 the pinions are indicated by the numeral l5. Each pinion is driven by a reversible motor it, which is under the control of the operator of the machine.

Up to the present time manufacturers of such excavating machines, particularly of the larger type frequently used in strip mining operations, have been unable to provide gear and pinion structures which will withstand for substantial periods of time the tremendous stresses imposed on them, as referred to above. The present improvements contemplate the utilization of power units located on the machine at points substantially removed from the axis it for cooperation with the motor driven pinions IS in accelerating and decelerating the swinging movements of the superstructure.

In Fig. 1 three such power units are shown.

One of the power units, designated generally by the numeral i'i, comprises an internal combustion engine it as shown in Fig. 2, which may be of an airplane type and which drives an air screw or propeller it. Another such unit, indicated generally by the numeral 251, comprises a similar engine 2! which drives an air screw 22. Such unit is shown mounted at the rear of the superstructure. A third similar unit indicated generally by the numeral 23, comprises an engine 24 which operates a propeller 25. In the structure shown in Figs. 1, 2 and 3 the propellers are of the reversible pitch type, that is, of a type the blades of which may be reversed to produce movements forwardly and rearwardly.

Any suitable means under the control of the operator in the cab of the machine may be utilized for controlling the reversing movement of the propeller blades. Such control means 26 are indicated diagrammatically and may be electrical,

hydraulic or mechanical, as preferred. By means of such control the blades of propellers it and 25 will exert moments in the same direction, while the blades of propeller 22 being on the opposite side of axis it will exert a moment in the direction opposite the direction of moments exerted by propellers it and 25, whereby the three propellers will mutually cooperate with the rack and pinion mechanism in producing swinging movement of the superstructure in one direction or the other under the control of the operator in the cab of the machine. Thus, when a bucket 21 has been loaded and elevation begun, the operator by manipulation preferably of a single control, will cause the motors of the three power units to accelerate from an idling speed t high speed or an intermediate speed in the proper cooperative directions ior exerting forces that are additive to the forces exerted by the pinions in swinging the superstructure in the desired direction. When the boom 23 of the machine has been swung to the point where the bucket 27 approaches or is over the selected position of discharge, the operator can reverse the pitch of the propeller blades of the three power units ii, and 23 and thereby decelerate the swinging movement of the superstructure and thereby cushion or reduce the stresses normally imposed upon the rack and pinion mechanism. Upon the reversal of direction of operation of the pinions [5 the superstructure is started on its return to an excavating position aided by the auxiliary power units. The pitch of the propellers may again be reversed for decelerating and arresting the swinging movements of the superstructure at the excavating position in cooperation with the control of the pinion operating motors l6. During the succeeding bucket loading interval the motors of the auxiliary power units merely idle or operate at a low speed. It will be seen that the forces exerted by the propellers are additive to those exerted by the pinions I5 in swinging the superstructure to and from IoaddiScharging position and thus relieve the pinions and the associated rack from a portion of the work otherwise required to be performed by them or enable the rate of swing to be accelerated and decelerated without imposing additional or unsafe loads on the pinions.

In Fig. 4 of the drawing there is illustrated an excavator of the shovel type that may be provided with propeller-power units similar to those described above with reference to Fig. 1. However, in Figs. 4 and 5 a somewhat different arrangement is shown which obviates the use of reversible pitch propellers in that at the outer end of the boom 29, as well as at the rear end of the superstructure 36 of the machine, there is shown propeller-power units arranged in pairs.

as shown more particularly in Fig. 5. In Fig. 5 which is a top plan view of the propeller-power units shown at the outer end of the boom, two motors are shown arranged in axial alignment and having propellers adapted to exert oppositely directed forces. Si in a direction for causing swinging movement in one direction, while motor 32 operates propeller 33 for causing swinging movement in the opposite direction. The pair of motors which are shown mounted at the rear of the superstructure 29 are arranged similarly to the motors shown at the outer end of the boom. Thus, motor 34 operates a propeller 35 in a direction to exert a force in the same direction as that exerted by propeller 3!. to operate and to be controlled in unison, while motor 36 which operates propeller 31, exerts a force tending to swing the superstructure about its vertical axis in the same direction as that exerted by propeller 33. therefore are arranged to operate and to be controlled in unison. 1

The power units illustrated in Fig. 4 likewise, are arranged for exerting forces which are additive to the forces exerted by the conventional? motor driven pinions 38 which mesh with the circular rack 39, whereby the stresses imposed upon the rack and pinion structure are or may be reduced. The motors of the power units shown in Fig. 4 are controllable by any suitable" means, electrical or otherwise, by the operator" in the cab of the machine. Control means are indicated diagrammatically by numerals 4B.

In Fig. 7 of the drawing a power unit is shown comprising an electrical motor 4! which drives a propeller 42.

either direction for exerting a force in a selected direction. Power units of the type shown in Fig.

7 may, if desired, be substituted for the power units shown in the preceding figures, and when.

operating the excavating machines themselves. when of the electrically operated type, a

The motor 30 operates propeller The motors 30 and 34 are designed The motors 36 and 32 The motor 4| preferably is of the: reversible type for operating the propeller in In Fig. 8 a further alternative structure is shown wherein an engine 53 is provided with a crank shaft 99 which at each end extends from the engine casing into operative relation with one of two clutches 35, 9 which are shown diagrammatically. The clutches when in driven engagement with the respective ends of shaft is are adapted to operate the propellers ll, 38 respectively. The propellers are selectively operable by operation of control means 49, 59 which extend from the clutches to the operators station in the superstructure 51. The propellers are rotatable in the same direction and hence are oppositely pitched, one to provide swinging effort in one direction and the other to provide swinging effort in the opposite direction under control of the operator. The engine 43 in Fig. 8 is shown mounted on the outer end of a boom 52 which may correspond to either boom 29 or 29 shown in Figs. 1 and i, respectively. Preferably a second engine having similarly clutch controlled propellers will be mounted at the rear of the superstructure for coaction with engine :13 in producing a swinging force on the superstructure in conjunction with the conventional swinging mechanism described above with respect to the preceding figures of the drawing.

The propellers employed as part of the power units need not be strictly of the airplane type, and where they are of the reversible pitch type it is desirable that they exert equal and maximum driving force in either position of extreme adjustment. Likewise the propeller employed in the electrical motor unit, such as is shown in Fig. '7, may be designed to exert equal driving force regardless of the direction of operation thereof.

While it is not contemplated that the auxiliary power units described need develop sufficient forces to swing the machine to and from load discharging positions independently of the conventional rack and pinion mechanism, the forces of such units being additive to the forces exerted by the rack and pinion mechanism relieve the latter of some of the stresses imposed thereon normally, and hence shutdowns by reason of breakage of such mechanism are reduced by the present improvements. Likewise, the mechanical advantage of the auxiliary units resulting from their being located as remotely as is feasible from the vertical axis of the superstructure enables such auxiliary units to accelerate and decelerate the normal rate of swinging move ments of the superstructure, and hence to increase the earth moving capacity of a given machine by reducing the time intervals between successive loads.

While various structures illustrative of the improvements have been shown and described, various changes in mechanical details may be resorted to within the spirit of the invention.

We claim:

1. Excavating apparatus comprising a mobile carriage, a superstructure pivotally supported by the carriage for swinging movement on a vertical axis, said superstructure comprising a boom extending laterally therefrom, power operated mechanism on the carriage and superstructure for swinging the latter about said axis, and a power operated air screw mounted on said boom for exerting a force that is additive to the force exerted by said mechanism in swinging said superstructure.

2. Excavating apparatus comprising a mobile carriage, a superstructure pivotally supported by the carriage for swinging movement on a vertical axis, said superstructure comprising a boom extending laterally therefrom, power operated mechanism on the carriage and superstructure for swinging the latter about said axis, and power operated air screws, one mounted on said boom and the other on the superstructure on the side of the axis remote from the boom, for exerting forces in directions that are additive to the forces exerted by said mechanism in swinging the superstructure about said axis.

3. Excavating apparatus comprising a mobile carriage, a superstructure pivotally supported thereon for swinging movement about a vertical axis to and from excavating and load discharging positions, controllable mechanism for swinging said superstructure about said axis in either direction, and power units on said superstructure arranged in pairs on opposed sides of the axis of the superstructure, said pairs of units having air screws arranged for alternate operation for exerting forces in opposite directions that are additive to the forces exerted by said mechanism in swinging said superstructure in the respective directions.

THOMAS C. MULLINS. WILLIAM E. MULLINS, JR.

' file of this patent:

UNITED STATES PATENTS Number Name Date 906,123 Elkin Dec. 8, 1908 1,198,501 Wintermute Sept. 19, 1916 1,374,787 Walker Apr. 12, 1921 1,722,922 Johnson July 30, 1929 1,842,125 Schwarz Jan. 19, 1932 1,855,892 Schiebeler Apr. 26, 1932 1,863,989 Liisanantti June 21, 1932 1,917,955 Dierks July 11, 1933 1,994,488 Sikorsky Mar. 19, 1935 2,066,776 Bel Geddes Jan. 5, 1937 FOREIGN PATENTS Number Country Date 221,483 Great Britain July 23, 1924 

